1. Field of the Invention
The present invention relates to an extract of Polygonum multiflorum Thunb. ex Murray var. hypoleucum (Ohwi), especially to an extract of Polygonum multiflorum Thunb. ex Murray var. hypoleucum (Ohwi) for improving metabolic syndrome.
2. Description of the Related Art
Metabolic syndrome is a combination of medical disorders that increase a person's risk of developing cardiovascular diseases and diabetes. Metabolic syndrome affects a large number of people in a clustered fashion. Recently, with changing dietary habits and lifestyle, more and more people are being diagnosed as having metabolic syndrome that have symptoms including high blood glucose, high blood pressure or high blood lipid level.
Metabolic syndrome may specifically refer to insulin resistance syndrome.
Polygonum multiflorum Thunb. ex Murray var. hypoleucum (Ohwi), or Polygonum hypoleucum (Ohwi), is a special, endemic variety found in Taiwan.
Unlike the typical variety of Polygonum multiflorum, Polygonum multiflorum Thunb. ex Murray var hypoleucum (Ohwi) lacks the characteristic enlarged root part and is commonly used in folk medicine for treating cold, coughing or arthritis.
U.S. Pat. No. 5,531,991 teaches a composition and method for treating hyperglycemia, which utilizes an extract of the Chinese herb Polygonum multiflorum. The herb is extracted with 0.1 N NH4OH and centrifuged. A supernatant is applied to a Sephadex G-25 column. Three fractions are collected. One fraction exhibits a high insulin-potentiating activity in fat cell assays and is shown to lower blood glucose levels.
U.S. Pat. No. 6,200,569 teaches a composition and method for increasing insulin activity, which provides a composition comprising an insulin potentiating agent; such composition comprises one or more substances derived from a water extract of Polygonum multiflorum, Agaricaceae or Cinnamomum mairei. The invention also provides a method for treating hyperglycemia in a patient as an insulin-potentiating agent. The method can be used to decrease blood glucose, glycosylated hemoglobin or glucose level.
The foregoing prior arts relate exclusively to use of Polygonum multiflorum extract to control glucose level by stimulating the activity of insulin. However, the foregoing prior arts are not capable of use for modulating the blood lipid, nor improving metabolic syndrome.
Moreover, EP 1 829 519 A1 teaches a pharmaceutical composition comprising Polygonum multiflorum Thunb. which comprises Polygonum multiflorum Thunb. Fructus Crataegi, Salvia miltiorrhiza Bunge and Radix Notog inseng. The composition has an effect of lowering blood lipid and therefore can be used in preparation of drugs for treatment and prevention of hyperlipidemia. The invention also teaches a method to treat and prevent hyperlipidemia. However, the composition must be used as a whole. In addition, the foregoing patent did not disclose how to modulate blood glucose level nor to improve metabolic syndrome.
As disclosed herein, pharmaceutical compositions and food additives merely provide a single effect on decreasing either blood glucose or blood lipid; yet no related prior art has been taught for using Polygonum multiflorum Thunb. ex Murray var. hypoleucum (Ohwi), or Polygonum hypoleucum (Ohwi) for treating metabolic syndrome. Furthermore, the foregoing prior arts use the typical variety of Polygonum multiflorum. 
The population of patients with metabolic syndrome has been increasing. To discover a compound or composition, especially a natural plant composition having medical effects in preventing insulin resistance and further to improve metabolic syndrome is important in the field.